NOTE:
This
article is written in the same form as an article for a scientic journal:
all the literature used in writing it is carefully cited in the text,
so if you want to learn more about certain aspects of Octopus intelligence,
you can go to a university library and look up the origonal article -
ask the librarian to help you learn how to do this - you'll need these
skills a LOT, when you get to college!!

The same question about octopus behavior intrigued both authors, though
at different places and from different backgrounds. While watching an
Octopus vulgaris in Bermuda, the first author observed it sitting in its
sheltering den after a foraging expedition, where it caught several crabs,
took them home and ate them. Suddenly it jetted out directly to a small
rock about two meters away, tucked it under its spread arms and jetted
back. Going out three times more in different directions, it took up three
more rocks and piled the resulting barrier in front of the entrance to
its den. It held them in front with several arms and went to sleep. This
didn't look like random action, but planning. The second author came in
one morning to the Aquarium to find one of the giant Pacific octopuses
had been busy overnight. The gravel on the tank bottom was dug up, the
nylon cable ties that attached the undergravel filter to the tank had
been bitten through and the detached filter had been bitten or torn into
small pieces, which now floated on the water surface (experienced octopus
keepers know that Murphy's Laws seem to apply especially to octopuses!).
Again, this looked like a careful sequencing/planning of actions and learning
put to use, though the reasons weren't at all obvious. These observations
made both of us believe that octopuses could possibly be intelligent and
use their intelligence for unexpected purposes.

When humans think of intelligence, we think of ourselves. This anthropocentric
viewpoint is partly because intelligence has only really been studied
in vertebrates and partly because we see its evolution as leading to the
pinnacle called Homo sapiens. Until recently, there hasn't been any model
of how another completely separate group could show us how intelligence
might evolve differently than ours. Research on the octopuses is beginning
to provide that alternate model.

An octopus is very different from a mammal. It only lives about two years.
It has much less opportunity to gain and use intelligence than an elephant,
which has a 50 year lifespan and three generations of a family to lead
and learn from. Still, bees learn about flower locations from other bees,
and they live only a few weeks as adults. However, an octopus is also
not social; Humphrey (1976) suggested that intelligence has evolved to
solve social dilemmas. The young octopus learns on its own with minimal
contact with conspecifics and no influences of parental care or sibling
rivalry. However, the octopus has a large brain with vertical and sub-frontal
lobes dedicated just to storing learned information (Wells, 1978):
it has the anatomy for a robust, built-in intelligence.

But, it is not enough to know that the anatomy predicts an animal to be
intelligent without some idea of how it uses this ability. Investigations
at Naples in the 1950s and 1960s found that octopuses (or "octopi", if
you want to Get Latin!!) can learn a wide array of visual patterns, encoding
information mostly by comparing edges, orientations and shapes. They also
learned by touch, and tactile information seemed to be stored in a different
brain area than visual. Intent on just demonstrating learning abilities
at first, researchers did not follow up to find what octopuses were doing
with this learning in their ocean home. As ethology's (ie, the ethical
or "moral" side of science, which discourages direct experimentation on
intelligent animals) emphasis on observation of natural behavior in the
field began to fill the gap (see Lehner, 1998), the Naples studies ended,
and no linkage was made between abstract information storage and the use
of learning in daily life. Finally, this gap is being bridged by such
works as Hanlon and Messenger (1996), who provide an overview of cephalopod
behavior. But, even asking the right questions about octopus intelligence
is difficult, since we understand so little of their minds. Watching an
animal and wondering how it is organizing its world, then testing it to
see if your guesses have some foundation - that is very difficult indeed!
Still, we are starting to get some answers both by observing in the field
and by studying areas such as prey manipulation, personality and play
(yes, play!) in the octopus.

One of the insights into how we might view octopus intelligence came for
the first author when reading Neisser's (1976) definition of cognition
(ie, thinking) as "all the processes by which sensory input is transformed,
reduced, elaborated, stored, recovered and used." It seemed a focal
issue: what were octopuses in the ocean doing with the information that
learning studies said they could acquire? One study we undertook centered
on what we came to call the "Packaging Problem". The problem posed
was how an octopus could utilize a delectable clam enclosed in its hard
shell, - to get at the soft, delectable clam body. This is
the end result of what Vermeij (1993) called an "evolutionary arms race":
many predators evolved means of penetrating the hard shell the clam uses
to protect itself, which is held together by powerful muscles - sea stars
pull the valves apart, oyster-catcher birds pry them apart, moon snails
(Naticidae) drill a hole into the shell, and gulls drop the clam from
a carefully calculated height onto rocks or road pavement. But the octopus
goes these predators one better: it can use several different strategies
to solve this Packaging Problem, instead of just one or two!

Octopuses come well-equipped with an arsenal of different solutions for
use in feeding. They have the holding ability of hundreds of suckers and
the pulling power of the eight muscular arms, flexible because they are
boneless (see Mather, 1998 for arm movement capacity). Underneath, inside
the mouth at the junction of the arms, they have a parrot like twin beak
for biting. Also inside the mouth are two more useful structures, the
radula with teeth for rasping and the extendible salivary papilla. It
delivers cephalotoxin, a neuromuscular function blocker that can kill
a crab in several minutes (Boyle, 1990). Fortunately for us, only the
venom of Haplochlaena spp. octopuses (the famous "blue" octoupuses!) has
proven fatal to humans.

Since octopuses are well set up to "recover and use" information for solving
the problem of the clam's protection, we set out to determine what the
giant (up to 50 kg) Pacific octopus, Enteroctopus dofleini, would do to
get at three types of bivalves. When we offered them separately or together
at the Seattle Aquarium, octopuses ate many Venerupis (a Venus Clam) clams,
some Mytilus (mussels) and few Protothaca clams. The prey species were
each opened differently, however. The fragile mussel shells were simply
broken and the stronger Venerupis were pulled apart. The thick shelled
Protothaca were drilled with the octopuses' radula and salivary papilla,
or chipped with the beak, then injected with poison which weakened
the adductor muscle holding the valves together. The octopuses'
strategy to penetrate into the different clams varied.
When offered the clams opened ìon the half shell, the
octopuses changed preference and consumed both clam species, but hardly
any mussels. When they didn't have to work hard for the clam meat,
they liked Protothaca. Some clue that effort might be the reason for this
shift came when we measured the resistance to opening force of the adductor
muscles of the bivalves : Mytilus resisted until an average of 2.2 kg,
Venerupis, 3.6 kg, and Protothaca to 4.6 kg. Octopuses could also
shift their penetration strategies. When live Venerupis clams were wired
shut with stainless steel wire, the octopuses couldn't pull the valves
apart, so they then tried drilling and chipping as penetration techniques
(given empty weighted shells glued shut, the octopuses ignored them; they
were on to that trick right away!). This flexibility of strategies echoes
what Wodinsky (1969) found with Octopus vulgaris drilling Strombus gastropods.
These octopuses drilled through the shell apex to poison and weaken the
snails' adductor muscles. When he coated this part of the shell with latex,
they just pulled it off, then drilled as before. When he then
put on aluminum, they simply drilled through the metal and shell, but
when he coated it with impenetrable dental plastic they drilled elsewhere
on the shell, or pulled the snail out by sheer force. For both species
of octopus, the motto might be "do whatever works to get your meal!"
They were intelligently adapting the penetration technique to the clam
species presented and the situation in which they were placed.

The first author (Jennifer Mather) also noticed this pragmatism
(ie, a "whatever it takes to get the job done" attitude!) and identified
tool use by octopuses during field studies in Bermuda (Mather, 1994).
Tool use does not automatically denote learning but the range of uses
of one tool, water, also suggests the octopus is intelligent: circulation
of water in molluscan mantle cavities is primarily used for respiration
and removal of wastes, and secondarily for locomotion in scallops and
squid (Morton, 1967). Octopuses also use water jets through their flexible
funnel for tertiary (ie, additional) functions such as cleaning
out their dens. They gather an armful of rocks and sand under their web,
go to the den entrance and tilt the web upward, then blow the whole lot
out and away with a water blast from their funnel! Similarly, an
octopus holds a crab under the web, dismembers it, eats the flesh and
holds the cleaned out exoskeletal pieces. At meal's end, it tilts
up the web and blows the pieces outside, adding to a midden outside the
den. Scavenging fish attend octopuses when they go hunting, and when they
discard remains onto this midden. One of the techniques octopuses use
to repel these "pests" is to direct strong blasts of water jet at them
- like a water gun!! (Mather, 1992). On occasion, an octopus jets water
to repel human observers, and octopuses in the lab have jetted into the
faces of researchers or onto their delicate electrical equipment.

In the laboratory, octopuses adapt and use this water jet in a behavior
that has generally been considered exclusively of vertebrates: they play
(Mather and Anderson, 1999). We set out to prove that octopuses
(Enteroctopus dofleini in particular) play, deciding that being in a non-stimulating
situation except for having an item that they could manipulate, might
cause such activity. A floating pill bottle, which sometimes drifted in
the current from the water intake, was the item. We didn't expect social
play from a solitary animal, rather that the exploration that the octopus
mentioned at the start of this paper demonstrated so well by tearing apart
its tank would turn the focus of its behavior, as Hutt (1966) suggested,
from "what does this object do?" to "what can I do with the object?
Every octopus jetted at the floating toy at least once in the ten trials,
but only two of them reached the criteria for play. These were 1) regular
repetitions of 2) simple acts for 3) over 5 minutes, of pill bottle repulsion
toward the water inlet jet and return by it. One octopus set up a 2 minute
circuit of the bottle around the tank and a second jetted the toy straight
towards the water intake, getting a return in 30 seconds. This prompted
a long distance call from the more skeptical second author to the first,
in the middle of one of those busy academic days, with the simple message
"She's bouncing the ball!"

Play is a difficult and sometimes controversial area, as it does not delineate
a separate category of behaviors. Forms that are seen as play merge into
other categories of "useful" actions (Fagen, 1981). This example appears
to be a small glimpse of that continuum, change in the use of mantle water
circulation from its basic molluscan function to newer situations. Play
involves the detachment of actions from their primary context, and such
flexibility is both a basis and a sign of intelligence, whether it be
shown in a person or a fish or an octopus. It is the formation of a new
combination of information input and actions.

A third aspect of the lives of the octopuses which shows their capacity
for acquiring different responses is their possession of "personalities".
The impetus for this study came from the second author's work at
the Seattle Aquarium (Anderson, 1987). Volunteers are the backbone of
public institutions such as the Aquarium, and volunteers see animals a
little differently than scientists. They give individual names to three
species of animals in the Aquarium - the seals, the sea otters, and the
octopuses. There was "Leisure Suit Larry", named for a video game character
who would be cited daily for sexual harassment on the job for excessive
touching. There was "Emily Dickinson", who hid behind the tank's backdrop
and could barely be coaxed out. And there was "Lucretia McEvil",
whose destructive acts are featured at the beginning of this article.
Volunteers shied away from feeding her because she would try to pull them
down into her tank.

We decided to take this impression of differences between individuals
and systematize it: what would it mean to say that octopuses had
personalities, and into what categories might we fit them? So we started
an octopus vs octopus study of the small Pacific red octopus Octopus
rubescens. Instead of testing in a novel situation and calculating average
responses, we tested three everyday situations to find variation. The
situations were alerting, threat and feeding, and over three years 44
octopuses were tallied for nineteen responses. To find variation rather
than averages, we did some difficult and "advanced" statistics: a Factor
Analysis and then a Principal Components Analysis. What the first
does is to group behaviors into clusters of occurrence amongst individuals,
called Factors, and our analysis told us there were three Factors, described
below. The Principal Components Analysis changed these factors slightly
so they were not correlated with each other and could then be called Dimensions
of Personality. Each octopus (and any future one) could then be placed
somewhere on each of these dimensions, and could be given an Octopus Personality
Profile (Mather and Anderson, 1993).

Once the researcher has these dimensions, they can be assigned names.
In the octopuses' case we chose three: Activity, Reactivity and Avoidance.
So an Active octopus reacted to the threatening probe by grabbing it,
a Reactive one performed a set of behaviors that put distance between
itself and the threat and an Avoidant one tried to stay away from the
situation in the first place. This catalog of variation is interesting
by itself, but the dimensions occur in other animals as well. Fish, monkeys
and people differ on some variable often called Shyness, on another called
Emotionality and a third defined as Exploration or Activity. While the
dimensions were of course extracted from the responses by a human brain,
they are similar in phylogenetically (ie, gentically) distant animals
(see Gosling and John, 1999).

Why does this matter to the demonstration of intelligence? For one
thing, personality overlays intelligence. Autistic children's intelligence
is often hard to measure because they don't like people well enough to
cooperate with the testers. Patterson and Linden (1981) found the
gorilla Koko showed the same withdrawal in the middle of an intelligence
test; he got bored and started pressing the same button over and over.
One octopus in a group being tested for spatial memory "freaked out" at
being put in an open tank and circled the tank for ten minutes at a time
(personal observation). She never had a chance to learn the task. Was
she stupid? Povinelli, et al., (1993) tested chimpanzees for self recognition
and made sure to test many individuals to cover this variation. They concluded
that the differences were so high that individuals' intellectual level
would have been assessed as typical of quite different species, and not
just the one!

In addition, "personality" allows individuals to show intelligence.
If the sensory input is to be "transformed, reduced, elaborated, stored
recovered and used" (Neisser, 1976), it has to be on the basis of individual
variation. The intelligent animal can master variable environments by
using all these processes, and that leads us back to the topic:
what is intelligence like? Indeed, it may be the variable environment
that selects for intelligence, in a Darwinian "survival of the fittest"
sense: since many octopus species spend their early months in as plankton,
drifting to all sorts of different habitat-types: the octopus that settles
out of the plankton onto a rocky shoreline has to learn to find different
prey and avoid different predators than the one that finds its home under
the only rock on a sandy bottom. Without this ability to become different,
they won't survive. Coping with a variable environment is what will demonstrate
the asocial octopus's particular "take" on intelligence. Thus, the studies
of Fiorito et al. (1999) on the octopus's ability to open a glass jar
and Hanlon et al.ís (1999) assessment of the avoidance strategies
of O. cyanea to a threatening human also open a window on the octopusís
use of intelligence.

Perhaps it is this individual sensitivity to change, honed by intelligence
and variability, that has been the key to the success of both the cephalopods
and the higher vertebrates. Similarities that could lead us to understand
the evolution of intelligence in octopuses and humans are few, but thought-provoking:
1) neither group has the protection of exoskeleton, scales or armor,
2) both have evolved in complex environments, the octopod in the tropical
coral reef and the hominid in the savanna edge, and 3) both
have considerable variability among individuals and the ability of being
able to change their behaviour to help them survive. So, perhaps looking
at the octopuses through their intelligence, feeding flexibility, predator
avoidance, play, and personality helps us also look at aspects of ourselves,
from another angle!